In-vitro Seed Germination and Somatic Embryogenesis in Ailanthus excelsa Roxb.: A Medicinal Tree of Heaven

Abstract

Aim: This study aimed to induce in vitro somatic embryogenesis (SE) from germinated Ailanthus excelsa seedlings and evaluate the effect of various cytokinins on embryo development and shoot induction. Method: Mature, dry Ailanthus excelsa seeds were surface sterilized and cultured on MS medium with gibberellic acid (0.1–3.5 mg/L). In vitro germinated plantlets were sectioned and cultured in MS medium with 2.0 mg/L NAA, 0.1 mg/L ascorbic acid (an anti-browning agent), and 0.15 mg/L citric acid (an anti-browning agent) to induce callus. Callus was subcultured once every two weeks and transferred to liquid MS medium with NAA and/or BAP, Kn, or TDZ to promote SE. Embryos were further cultured on solid MS medium with BAP, alone or with Kn or TDZ, and ascorbic acid. Statistical analysis was performed by ANOVA and Duncan’s Multiple Range Test (p ≤0.05). Results: Seed germination was significantly improved from 3.3% to 26.7% with 1.0 mg/L gibberellic acid.  Callus derived from in vitro seedlings produced bipolar somatic embryos with the highest number (81.00 ± 3.90) achieved with 0.5 mg/L NAA.  The maximum shoot induction (7.33 ± 0.58 and 7.33 ± 1.00) occurred with 0.5 and 2.0 mg/L BAP, respectively. Growth regulator treatments significantly influenced SE (p = 0.055) and shoot induction (p = 0.004). Conclusions: Germinated seedlings served as effective explants for SE in A excelsa. Low concentration of NAA in liquid MS medium promoted SE, while BAP induced shoot formation. Although hyperhydricity was observed during shoot elongation. These findings lay the foundation for future work on somatic embryo conversion, artificial seed production, large-scale propagation, and conservation of A. excelsa Roxb.